1. Field of the Invention
The invention relates to an intraocular lens for the human eye.
2. Description of the Prior Art
It has been a continuing goal in ophthalmology to develop an intraocular lens which can be placed through the smallest incision possible. There have been four basic approaches to intraocular lens design to accomplish this task:
1. The development of intraocular lens implants made of flexible materials which are foldable and can be implanted through a small incision in their smaller, folded state, to then have the implant unfold to its full size within the eye. Examples of such foldable designs are seen in the patents of Clayman U.S. Pat. No. 4,634,441 and Mazocoo U.S. Pat. No. 4,573,998. PA0 2. The development of intraocular lens implants made of expandable materials which combine with water and which are implanted into the eye in their smaller, dehydrated state and then expand their volume once they are placed into the liquid-containing interior of the eye. Examples of this type of design are seen in patents U.S. Pat. Nos. 4,556,998 and 4,734,095 by Siepser, and U.S. Pat No. 4,710,194 by Kelman. PA0 3. The development of intraocular lens implants containing two or more separate or movable pieces which require construction once placed within the eye. In some designs, the pieces are connected together but require repositioning (such as sliding) within the eye after implantation. Examples of this type of design are seen in U.S. Pat. No. 4,056,855 by Kelman, U.S. Pat. No. 4,636,210 by Hoffer, and U.S. Pat. No. 4,693,716 by Mackool. PA0 4. Intraocular lens implants constructed to have an inflatable optic chamber or compartment which is expandable within the eye by means of injection of a suitable fluid-like material into the initially deflated chamber which then expands to produce the optic when completely inflated. This type of design is seen in U.S. Pat. No. 4,585,457 by Kalb, U.S. Pat. No. 4,693,717 by Michelson, and U.S. Pat. No. 4,373,218 by Schachar.
Presently, with currently available technology and materials, it appears that the inflatable type of intraocular lens, which can be implanted in its uninflated, rolled up or compressed condition and then re-expanded in the eye with injection of the proper fluid-like material, stands the best chance of being the implant design implantable through the smallest incision. However, all of the existing inflatable designs proposed to date involve inflating the optic and that is a very unacceptable design feature because, by involving the optic in the inflation process, the optical quality of the implant is necessarily affected by and dependent on the inflation process. More specifically, the optical quality and function will depend on the exact volume and quality of fluid-like material injected during the inflation process, and the skill of the surgeon performing the inflation. Also, the possibility of leaks from the inflated optic cavity might result in a change in the optic shape (and therefore its optical power) and forever threatens the future optical quality of the implant. This dependency of the optical quality (and therefore the implant's ability to restore good vision to the patient) on the inflation of the optic is a serious and permanent design flaw for any inflatable design involving the optic. This possible optical variability is also a potential problem in those designs in which the optic dimensions will change with the combination of the optic material with fluid, such as the designs of Siepser. To a lesser extent, the optical quality of foldable materials is a potential problem which has been largely overcome through materials development. Potentially, the problems of the inflatable optic designs can likewise be overcome, however, there does not appear to be a practical and usable solution available in the near future.
Therefore, it would be desirable to develop an implant design which incorporates the advantageous features of inflation for volume reduction/enlargement to allow implantation through the smallest incision possible, and yet has an optic of established and constant optical quality which is independent of the inflation mechanism. None of the described inflatable designs by Kalb, Schachar, Michelson or any other person incorporate inflatable haptics as part of their design. Their designs are essentially those of an inflatable or expandable optic and therefore contain the optical problems mentioned above.